Coated fabric



Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE COATED FABRIC poration of Delaware No Drawing. Application January 5, 1934, Serial No. 705,458. Renewed June 18, 1936 2 Claims.

This invention relates to the art of coating, and more particularly to the manufacture of improved coated fabrics of the type having a coating of asphaltic materials applied over a flexible fabric sheeting.

Rubber coated fabrics are especially suitable for making various kinds of artificial leather products such as automobile top material. A problem that has been of great concern to the manufacturers of artificial leather for use as automobile top material is that of the development of a finish for said material which is as durable as the finish on the car with respect to luster retention and freedom from checking, cracking, and chalking. Among the most successful finishes proposed for this purpose are those containing asphalt, particularly those containing petroleum asphalt such as disclosed and claimed in U. S. Patent 1,795,199 issued to J. R. Couture. While the prior art petroleum asphalt varnishes have good luster retention, they fail to meet fullythe requirements of an automobile top material in respect to initial flexibility and toughness. Inasmuch as petroleum asphalts are limitedly compatible with bodied drying oils the proportion of bodied drying oil that can be homogeneously combined with the petroleum asphalt is definitely limited. Moreover, the luster retention qualities of petroleum asphalt-bodied drying oil varnishes falls off rapidly as the proportion of drying oil to asphalt is progressively increased. If sufficient bodied drying oil is added to the asphalt to give a finish which is flexible and tough initially, a finish is obtained which has both poor initial luster and poor durability on outdoor exposure. It is evident, therefore, that so far as petroleum asphalts are concerned their use in the manufacture of automobile top material finishes is limited to varnishes of relatively short oil length.

Another type of awhaltic varnish which is used vs a finish for automobile top material is that based on gilscnite. These varnishes have very desirable initial properties, since they have high Moreover,

taining gilsonite as the main asphaltic constituent have a very serious defect, namely, they dull and develop a, brown chalk after exposure to the weather for only a short period of time.

We have discovered a way for overcoming this 5 tendency of gilsonite varnishes to chalk and lose their luster upon exposure to the weather. Our invention is based upon the discovery that heavy pigmentation of gilsonite-drying oil varnishes with carbon black eliminates chalking and dulling upon exposure. Heavy pigmentation of gilsoniteoil varnishes with carbon black to reduce chalking and improve luster retention is a most unusual and radical departure from prior art practice, as it was heretofore believed that increased pigmentation would lead to increased chalking and dulling. However, we have discovered that if the carbon black content exceeds a certain 'minimum amount, as disclosed hereinafter, the

tendency of gilsonite-oil varnishes to chalk upon exposure is eliminated, and at the same time the luster retention qualities are remarkably enhanced.

This invention therefore has as an object the manufacture of artificial leather products comprising a flexible fabric sheeting base such as a rubber coated fabric, pyroxylin coated fabric, or oil varnish coated fabric, having a top coating of a gilsonite-drying oil varnish which is in a marked degree free from the defects exhibited by gilsonite-drying oil varnishes heretofore used. A further object is the production of a rubber coated fabric of the kind just mentioned which possesses superior durability, retention of gloss, and high resistance to chalking on outside exposure for long periods'of time. Other objects will appear hereinafter.

We have discovered that a much higher degree of pigmentation than has been previously practiced in the manufacture of gilsonite var- 40 nishes for finishing rubber coated fabrics results in a marked improvement in the properties most desired in artificial leather products having a rubber coated base, pyroxylin coated base or oil varnish ,coated base, this improvement being particularly noticeable and particularly unexpected in the high resistance of the finishing coat against chalking and in the fact that high pigmentation is not accompanied by loss of initial luster.

The following are examples of pigmented gilsonite-oil varnishes suitable for the practice of our invention.

Example I Parts Gilsonite 10.50 Bodied linseed oil 15.28 Bodied China-wood oil 13.86 Iron resinate (7.2% Fe); 1.89 Prussian blue (45.5% Fe) 0.47 Carbon black 8.00 Turpentine substitute 50.00

in less than one month exposure to the weather.

Example II Parts Gilsonite 13.44 Bodied linseed oil 23.01 Bodied China-wood oil 1.91 Lead-manganese resinate drier (6.42%

Pb, 1.5% Mn) 0.64 China clay 10.00 Carbon black 7.50 Turpentine substitute 43.50

The above is approximately a 30 gallon gilsonite varnish containing a mixture of Chinawood and linseed oils bodied with lead-manganese resinate drier, and approximately 31% pigment on the solids content of the 'varnish.

The above varnish when used as a baked finish for rubber coated fabrics has initial properties similar to those of the varnish of Example I. After six months exposure to the weather under the same conditions as the varnish of Example I it shows a high order of luster retention, and chalks but slightly. A similar unpigmented varnish fails badly by chalking and dulling in less than one month.

Example III Parts Gilsonite 7.54 Bodied linseed oil 14.25 Bodied China-wood ofl 12.93 Iron resinate (7.2% Fe) 1.78 Prussian blue (45.5% Fe) 0.46 Carbon black 8.69 Turpentine substitute 54.35

The above is approximately a 46 gallon gilsonite varnish containing China-wood oil bodied with iron resinate, linseed oil bodied with Prussian blue, and approximately 19% pigment on the solids content of the varnish.

This varnish when used as a baked finish for rubber coated fabrics has high initial luster and a deep black color. After six months exposure to severe weather conditions, its luster retention qualities are practically the same as those of the varnish of Example I. A similar unpi mented varnish fails badly by chalking and dulling in less than one month exposure to the weather.

Example IV Parts Gilsonite 7. 54 Bodied China-wood oil 27.18 Ferric resinate (7.2% Fe) 3.78 Carbon black 8.69 Solvent naphtha 52.81

The aboveis approximately a 46 gallon gilsonite varnish containing China-wood oil bodied with iron resinate, and approximately 18% pigment on the solids content of the varnish.

This varnish is practically identical in its initial quality and luster retention with the varnish of Example III. A similar unpigmented varnish fails badly by chalking and dulling after about one months exposure to the weather.

The above is approximately a 67 gallon gilsonite varnish containing China-wood oil bodied with iron resinate, linseed oil bodied with Prussian blue, and approximately 38% pigment on the solids content of the varnish.

This varnish when used as a baked finish for rubber coated fabrics has high initial luster, and is flexible. After six months exposure to the weather it still retains its initial luster fairly well, although it -has some tendency to chalk and bronze. Thedegree of chalking and bronzing that develops, however, is not serious. A similar unpigmented varnish fails by chalking and dulling in less than one month's exposure.

Example VI Parts Gilsonite 7.54 Resin A (Acid No. 15.4) 27. 18 Iron resinate (7.2% Fe) 3.78 China clay 10. 00 Super-spectra black 7.00 Solvent naphtha 44.50

The above is approximately a 46'gallon gilsonite varnish containing a polyhydric alcoholpolycarboxylic acid resin, designated Resin -A,

iron resinate, and approximately 31% pigment on the solids content of the varnish.

Resin A, used in the above composition, was formed from the following ingredients, using the proportions indicated:

Parts Glycerol 11. 05 Phthalic anhydride 7. 30 Linseed oil acids -1 67. Rosin 13. 70

The varnish of Example VI when used as a baked finish for rubber coated fabrics has high initial luster, is flexible, and has a deep black color. After six months exposure to severe weather conditions the luster retention qualities of this varnish are good, although it has some tendency to chalk and bronze slightly. A similar unpigmented varnish fails badly by chalking and dulling in about one month.

Example VII Parts Gilsonite 10.81 Resin B (Acid No. 19.1) 26.78 Iron resinate (7.2% Fe) 3.72 China clay 6.00 Carbon black 12.00 Solvent naphtha 40.69

The above is approximately a 30 gallon gilsonite varnish containing a polyhydric alcoholpolybasic acid resin, designated Resin B", iron resinate, and approximately 30% pigment on the solids content of the varnish.

Resin B, used in the above composition, was

made from the following ingredients, using the proportions indicated:

The above is approximately a 46 gallon gilsonite varnish containing a synthetic mixed glyceride, designated Mixed Glyceride A, iron resinate, and approximately 15% pigment on the solids content of the varnish.

Mixed Glyceride A, used in the above composition, was prepared from the following ingredients, using the proportions indicated:

Parts Glycerol 8.77 Linseed oil acids 22.77 China-wood oil acids 45.52

R/osin 22.94

The varnishes of Examples VII and VIII when used as baked finishes for rubber coated fabrics have high initial luster and good color. After six months exposure to theweather their luster retention qualities are very good. The varnish of Example VII chalks slightly less, and has somewhat better luster retention qualities than the varnish of Example VIII. This, we believe, is a consequence of its higher carbon black content. Similar unpigmented varnishes fail badly by dulling and chalking in about one month exposure.

In making our improved artificial leather p:oducts the varnishes are preferably applied over the uncured rubber, and the varnish .dried by heating the system at a temperature which is suitable for the vulcanization of the rubber. In a modification of this process, which gives even better results in respect to initial appearance and durability, the varnishes are applied over an intermediate coat of oil varnish. In the one coat system outlined above, it is usual to bake at 240 F. to 270 F. for two to four hours to vulcanize the rubber and dry the varnish. In the two coat system, the intermediate coat of oil varnish is usually dried by baking at 240 F. to 270 F. for fifteen to thirty minutes, the final coat of highly pigmented gilsonite varnish applied, and the system baked at 240 F. to 270 F. for two to four hours to vulcanize the rubber and dry the final coat of asphalt varnish. The particular temperature at which the system is baked ineither the one coat or two coat systems, is determined by the composition of the rubber compound. Although the invention has been described with particular reference to the finishing of rubber coated fabrics, we wish it understood that the varnishes of this invention are also particularly valuable for use as undercoats for short oil asphalt varnishes, as automobile fender enamels, as lamp and pipe enamels, and

for general usage in the finishing of metal and wood surfaces. They are also useful as dressings for automobile top material, as touch-up enamels for metal surfaces, and in the manufacture of roofing material by impregnation of paper and otherbibulous materials.

' The most useful of the highly pigmented gilsonite varnishes described herein are those of from 20 to gallon oil length. By a gallon length in the varnish trade is meant a gallon of oil to pounds of gum. Accordingly, a gallon oil length as used herein designates 8 pounds of oil per '100 pounds of asphalt and our compositions therefore contain from about 160 to 560 pounds of oil per 100 pounds of asphalt.

The high proportion of pigment, which may consist whollyor in part of carbon black within the limits expressed below. is an essential feature of our invention. The carbon black content must not constitute less than 12% of the combined weight of the gilsonite and oil, but should not constitute more than the weight of the oil constituent less one and one-fourth the weight of the gilsonite. When the composition contains an inert pigment in addition to the carbon black, the total amount of pigment should not exceed about 55% and preferably should not be over about 40% of its total solids content. Thus,

in a thirty gallon varnish which contains 240 pounds of oil to 100 pounds of asphalt the maximum and minimum amount of carbon black by the above definition would be about 41 and pounds, respectively. The total amount of p'gment that can be used, if inert pigment is also included, is preferably not over about 40% of the total solFds content of the varnish. The total solids content in the present case is 240 pounds of oil plus 100 pounds of asphalt plus total pigment.

A very definite improvement in luster retention and freedom from chalking is obtained as the carbon black content of gilsonite-oil varnishes is increased from 10% to 12%. This is shown by the fact that a varnish containing 10% carbon black (based on the total solids content of the varnish) is only slightly better in its luster retention qualities and freedom from chalking than a similar unpigmented varnish. On the other hand, a. similar varnish but containing 12% carbon black has good luster retention and chalks but slightly even after six months exposure to the weather. These results clearly show that it is not merely a matter of heavy pigmentation because a varnish containing 10% carbon black is a heavily pigmented .varnish, but that there is a critical limit of carbon black content below which the improvement in luster retention and elimination of chalking claimed herein is not realized. As pointed out above gilsonite-drying oil varnishes containing about 12% carbon black (based on the total solids content of the varnish) have good luster retention and are relatively free from chalking even after six months exposure to weather. As the carbon black content of these varnishes is increased from 12% to 16% a very definite improvement in luster retention is obtained. In fact, a varnish containing 16% carbon black retains its initial luster to a remarkable degree, even after one year of severe exposure to the weather. In general, we prefer to use not more than about 20% carbon black in varnishes varying in gallon length between 20 and 30 gallons. In varnishes varying between 30 and 40 gallons in oil length we prefer to use about 20 to 30% carbon black and in varnishes varying from 40 to 70 gallons in oil length up to about 40% carbon black. A 70 gallon varnish containing up to carbon black has excellent luster retention and is relatively free from chalking after six months exposure to severe weather conditions, but the initial film qualities of such a varnish are not as satisfactory as those of a similar finish containing 40% carbon black. It is for this reason that we generally prefer not to use over about 40% carbon black in these compositions.

In the preparation of the highly pigmented gilsonite varnishes described herein, the preferred procedure is as follows: A varnish is prepared by heat-treating the oil or oils with the drier and subsequently blending with the required amount of asphalt or natural bitumen solution. A pigment dispersion is prepared by grinding the desired pigment into this varnish. The finished varnish is made by subsequently adding unpigmented varnish to the pigment dispersion to give the desired amount of pigment. The thinners employed for making the solutions of the asphalt and the solution of the oils may consist of mineral spirits, toluene, turpentine, solvent naphtha, and mixtures thereof.

While the above method of properation of the varnishes of this invention represents the preferred embodiment, the use of other methods of preparation is not precluded.

The carbon black used in the formulation of the gilsonite varnishes may be any one of the several forms of this pigment, such as the various gas blacks, channel blacks, bone blacks, superspectra black, microcosmic black, etc. The inert pigments are those used in paints and varnishes primarily for their bulking value. These pigments contribute little in the way of hiding power and opacity to the paint or varnish and are unreactive with the vehicle either initially or upon aging. China clay, asbestine, super-floss, talc, and kaolin are typical examples of these inert pigments.

In referring to the oil constituent of the varnish, the term drying oil as used herein means the natural drying or semi-drying oils, the synthetic oils including the synthetic mixed glycerides and the oil modified polyhydric alcoholploycarboxylic acid resins which when synthesized in the presence of relatively large amounts of oil or oil acids may be viewed as modifled drying oils. These latter products may be made by heat-treating a mixture of the fatty oil and polyhydric alcohol and heat -treating the resulting material with polycarboxylic acid. If the oil acids are used these may be heated simultaneously with the other ingredients.

By the term gilsonite as used herein, we mean a species of natural bitumen including dark colored, comparatively hard, and relatively nonvolatile solids, composed principally pf saturated hydrocarbons, substantially free from oxygenated bodies and crystallizable paraflins, sometimes associated with mineral matter, the non-mineral constituents being soluble in carbon bisulfide, carbon tetrachloride, benzene, and; other aromatic hydrocarbons.

The substitution of an inert pigment such as china clay for the carbon black substantially beyond the limits set forth results in a varnish having poor durability when applied to rubber coated fabrics.

As will be apparent from the examples, our

highly pigmented gilsonite varnishes show a remarkable improvement in resistance to chalking when they are used as finishes for rubber coated fabrics. We have exposed a rubber coated fabric having a top coating of the varnish of Example III to the sun and weather for six months and have also similarly exposed two rubber coated fabrics, one which had a top coating of the same gilsonite varnish without carbon black and the other which had a top coating of the same gilsonite varnish containing 8% carbon black, an amount less than that required for the practice of our invention. The rubber coated fabric finished with the varnish of Example III retains its initial luster to a remarkable degree and is practically free from chalking even after six months exposure to severe weather conditions. Even after one year exposure to severe weather conditions this varnish still retains the major portion of its initial luster and is remarkably free from chalking. The rubber coated fabric finished with the gilsonite varnish containing no carbon black failed very badly by dulling and chalking after about one month exposure to severe weather conditions. The rubber coated fabric finished with the gilsonite varnish containing.8% carbon black failed badly by dulling and chalking after about three months exposure to severe weather conditions. degree after only two months exposure than the varnish of Example III does after exposure for one year under similar conditions.

The high resistance to chalking and long retention of the initial high luster and deep black color of our improved artificial leather products This varnish chalks to a far greater upon long exposure to direct sunlight is alto-v sonite varnishes used as finishes for rubber coated fabrics. It should be observed, also, that this high amount of pigment does not with all kinds of asphalt result in this major improvement in luster retention and resistance to chalking.

Thus, a varnish simflar to Example I having petroleum residue asphalt substituted for the gilsonite fails by chalking after about three month's exposure, whereas, the varnish of Example I retains the major portion of'its initial luster and is practically free from chalking after one year continuous exposure to severe weather conditions. Our finish for rubber coatedjabrics is, moreover, an improvement over the asphaltic varnishes heretofore used with respect to the properties of durability, toughness, flexibility, freedom from flaking, and long retention of original luster.

As many apparently widely difierent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the following claims.

We claim:

1. As an article of manufacture, a rubber coated fabric sheeting having a top coat of dried varnish comprising gilsonite, drying oil vehicle and carbon black, the drying oil vehicle and gilsonite being present in the proportion of from about 160 to 560 .pounds of the drying oil vehicle per 100 pounds of gilsonite, the carbon black being present in an amount not less than about 12% of the combined weight 01 the gilsonite and oil vehicle, and not more than the weight of the oil less one and one-fourth the weight of the gilsonite.

2. As an article of manufacture, a rubber coated fabric sheeting having a top coat of baked varnish comprising gilsonite, drying oil vehicle and pigment, the drying oil vehicle and gilsonite being present in the proportion of from about 160 to 560 pounds of the oil vehicle per 100 pounds of gilsonite, said pigment consisting of not more than'40% of the total solids of the varnish and comprising carbon black in an amount notless than about 12% of the combined weight oi! the gilsonite and oil vehicle, and not more than the weight of the 011 less one and one-fourth the weight of the gilsonite.

ALFONSO M. ALVARADO. HAROLD J. BARRETT. 

